But when speaking about the existence of a God and the opposite of goodness (sin and evil) I don't think we should get bogged down in technical terms like "hot" and "cold". It's not the exact scientific meaning of "hot" and "cold" that matters, but rather the point was a symbolic reference to the relationship between hot and cold. So your argument is valid I must say, but it side-steps the message of the student's argument: evil doesn't exist, God exists and in his absence you'll find sin. Energy exists, and in its absence you find a void (cold and dark).

So did God create evil? Well getting away from scientific definitions, it can be shown with what I think to be a witty argument but perhaps not scientific, that God is not evil. It still can't be proven, and can be debated forever, but I thought the point was pretty well driven home.